METHOD OF FORMING A CLOSURE CAP HAVING A HEAT SHRINKABLE TUBULAR ELEMENT THEREOVER

• US 3,844,861 A
• Filed: 12/19/1972
• Issued: 10/29/1974
• Est. Priority Date: 11/19/1971
• Status: Expired due to Term

• Current Assignee: Edwin M. Irish Jr
• Original Assignee: Edwin M. Irish Jr
• Inventors: Irish, Edwin M. Jr.
• Primary Examiner(s): Whitby, Edward G.
• Application Number:
  US05/316,547
• Time in Patent Office: 679 Days
• Field of Search: 215/38A,42 156/69,84,85,86,250
• US Class Current: 156/69
• CPC Class Codes: B29C 63/423 specially applied to the mass-production of externally coated articles, e.g. bottles
• CPC Class Codes: B65D 39/02 Disc closures discs with flanges B65D39/04
• CPC Class Codes: B65D 41/54 Caps or cap-like covers made of shrinkable material or formed in situ by dipping, e.g. using gelatine or celluloid
• CPC Class Codes: B65D 45/00 Clamping or other pressure-applying devices for securing or retaining closure members screw-threaded or bayonet connections between stoppers or caps and containers B65D39/08, B65D41/04, B65D41/34; expansible stoppers B65D39/12; for pressure vessels in general F16J13/00
• CPC Class Codes: Y10T 156/1052 with cutting, punching, tearing or severing

Abstract

A milk bottle cap, apparatus and method, especially adapted as tamperproof closures for plastic milk bottles and the like. The bottle cap comprises a laminated disc structure containing a top layer of a rigid material, preferably an impervious plastic material, an intermediate layer which can be aluminum foil or the like, and a plastic foam disc for contact with the bottle opening. The disc, when placed on the bottle opening, is then sealed in place over the bottle opening and maintained in place by a heat shrink tube which is heat shrunk around and partially over the closure disc, and sealed thereto, and having a depending skirt in intimate sealing contact with the threds on the neck of the bottle. A tear strip is provided to initially break the seal to permit removal. The heat shrink material has sufficient strength and rigidity whereby the cap can be re-engaged, after removal, on the bottle threads for reclosure of the bottle.

Claims

1. The method of forming a closure cap for threaded neck plastic containers and the Like including a laminated disc adapted to engage over and in sealing relationship with a container opening and a heat-shrinkable plastic tube comprising:

a. passing pre-coated aluminum foil over a coating roll and applying an adhesive on the reverse side of the foil;

b. electrically heating the foil to dry the applied adhesive and activate the coating adhesive;

c. joining the heated foil with a top sheet and a bottom sheet and applying pressure to the juxtaposed sheets to form a permanent composite laminated sheet;

d. cutting discs from said laminated sheet; and

e. placing a tube of heat-shrinkable plastic material over a disc of the laminate and applying heat to partially heat-shrink the tube into engagement with the disc partially extending over the top thereover and with a depending skirt adapted for heatsealed engagement with and over the threaded neck of a container by further heat-shrinking subsequent to placement of the cap on a container.

2. A method as claimed in claim 1, wherein the combined sheets are passed through and between upper and lower pressure rolls, one said roll being heated to facilitate bonded adhesion.

3. A method as claimed in claim 2, wherein the upper sheet consists of polyvinyl chloride and the lower sheet consists of polyolefin foam material, the aluminum foil coating consisting of a vinyl heat-seal coat and the aluminum to polyolefin adhesive consists of a water-base pressure sensitive adhesive.

4. The method of manufacturing a closure cap as claimed in claim 1 comprising:

a. placing a laminated disc on a die;

b. cutting and placing a section of heat-shrink tubing on said die surrounding and extending above said disc;

c. shrinking the tube over the disc in partial overlapping engagement therewith and depending therefrom as a skirt;

d. heat-sealing the disc and tube;

e. cooling the sealed tube and disc; and

f. ejecting the finished cap from the die.

5. A method as claimed in claim 4 wherein said discs are cut from a continuous sheet of laminated material and placed on said die in a continuous production of the caps.

6. A method as claimed in claim 4 including the step of peripherally perforating or otherwise scoring said tubing to form a tear strip thereon prior to placement on the die.

7. The method of claim 6 including cutting and forming a tear strip tab and relief hole in the tube for coacting with the tear strip subsequent to shrinking of the tube around and partly over the disc.